Centrifugal pump



I Dec. 17, 1968 H. M. POLLAK ETAYL 3,416,456

CENTRIFUGAL PUMP Filed Nov. 14, lessr/a. L 54 52 m1 /6 E /2 68 E 34 M F/ 3 Q IIVV'A/TORS HENRY- M. POLL/1K ROBERT s. POLLA/f ATTORNEYS;

United States Patent 3,416,456 CENTRIFUGAL PUMP Henry M. Pollak, 1235 Queen St., and Robert S. Pollak, 1007 N. Warren St., both of Pottstown, Pa. 19464 Filed Nov. 14, 1966, Ser. No. 594,001 3 Claims. (Cl. 103-113) ABSTRACT OF THE DISCLOSURE The centrifugal pump of the present invention is of the self-priming type having first and second volute discharge ports providing communication between the pumping chamber and the air separator outlet chamber. The volute discharge ports are generally diametrically opposite one another with one of the ports being below the axis of the impeller. A recirculation port provides communication between the outlet chamber and the bottom of the pumping chamber. The recirculation port is spaced from said one volute discharge port by an arcuate distance of less than 120 degrees. Said one volute discharge port performs no function during priming.

In the design of self-priming centrifugal pumps, an effective seal must be maintained so that the atmosphere air cannot short circuit and return to the suction line during the priming cycle. Where multiple discharge ports are employed, it is generally necessary to keep the air separator outlet chamber substantially full of liquid in order to prevent short-circuiting. Such designs requiring a substantially full outlet chamber in order to effect priming have drawbacks since the full chamber is not a practical feature in operation. In the process of shutdown and start-up, some liquid is lost and hand-filling is frequently required. In the pump of the present invention, a proper seal is maintained by the disposition and location of the volute discharge ports.

In the design of self-priming centrifugal pumps, a recirculation of the priming water into and out of the impeller must be provided. It has been suggested heretofore to provide a recirculation point at or near the periphery of the impeller. In some designs, this recirculation port takes the form of a second volute which acts as a recirculation port during the priming cycle and constitutes a volute discharge port during the pumping cycle. Designs which simply provide a hole in the volute for recirculation during priming necessarily decrease efficiency during the pumping cycle. The reason for this is that energy conversion (velocity to pressure) does not occur as liquid flows through the hole in the same manner as it does in a volute. In the pump of the present invention, such energy loses are minimized.

In the pump of the present invention, first and second volutes are provided generally diametrically opposite one another. One of the volutes is below the axis of rotation of the impeller and performs no function during the priming cycle. The discharge port of said one volute is placed in an underwater position in order that the proper seal is accomplished. A recirculation port is placed adjacent the bottom of the pumping chamber :and less than 90 arcuate degrees from the discharge port for said one volute. Since the natural process of air rising will cause the liquid in the outlet chamber to be more nearly free of air adjacent said recirculation point, this will allow recirculation of the more nearly air-free water and result in faster priming.

For a given size pump, the throat area of the volute is essentially fixed. Substantially identical pump-hydraulic performance can be obtained by making a dual volute pump wherein summation of the throat areas of the two volutes adds up to the total area of a single volute pump.

3,416,456 Patented Dec. '17, 1968 In the present invention, the throat area of the individual volutes can be lessened, thereby making it easier to maintain an effective seal in the priming of the pump and thereby require a smaller amount of water in order to prevent short circuits.

0n pumps employing a single volute with a recirculation port, a close clearance is required between the cutwater diameter of the volute and the periphery of the impeller. Because of the easier sealing effect of the present invention, the close clearance between the cutwater diameter of the volutes and the impeller periphery is no longer necessary.

By locating the recirculation port less than arcuate degrees from the nearest volute discharge cutwater, the amount of liquid discharged from the port during the pumping cycle is minimized. Because of the sealing problem, single volute pumps normally require the circulation port to be located at positions up to 270 arcuate degrees from the discharge cutwater. As a result thereof, approximately 75 percent of the water discharged from the impeller is subject to leakage out of the recirculation port during the pumping cycle thereby seriously affecting efficiency.

It is an object of the present invention to provide a novel self-priming centrifugal pump.

It is another object of the present invention to provide a dual volute self-priming centrifugal pump wherein one volute does not function during priming since substantially all liquid entering a recirculation port less than degrees from said one volute and adjacent the bottom of the pumping chamber is discharged by the impeller through the other volute.

It is another object of the present invention to provide a self-priming centrifugal pump which is easier to prime and is more eflicient.

It is another object of the present invention to provide a dual volute centrifugal pump which is simple, economical to manufacture, andreliable.

Other objects will appear hereinafter.

For the purpose of illustrating the invention, there is shown in the drawings a form which is presently preferred; it being understood, however, that this invention is not limited to the precise arrangements and instrumentalities shown. 1

FIGURE 1 is a sectional view of the pump of the present invention.

FIGURE 2 is a rear elevation view of the pump in FIGURE 1.

FIGURE 3 is a sectional view taken along the line 33 in FIGURE 1.

Referring to the drawing in detail, wherein like numerals indicate like elements, there is shown in FIGURE 1 a centrifugal pump in accordance with the present invention designated generally as 10. The pump 10 includes a casing designated generally as 12 and which can be made from cast aluminum or other materials. While the casing 12 is preferably cast from one piece, it may be comprised of two or more portions bolted together.

The casing 12 includes side walls 14 and 16 connected to a bottom wall 18, a top wall 20, and end walls 22 and 24. An air separator outlet chamber 13 is defined by the walls of the casing 12.

A separator wall 26 is provided within the chamber 13. Wall 26 is provided with a suction port 28 providing communication between a suction chamber 30 on one side of wall 26 and the pumping chamber 32 on the other side of wall 26. Wall 26 is integral with the side Wall 16 by means of volute walls 36 and 38. Wall 26 is also integral with the side wall 14 by means of the generally conical annular wall 34 which defines the cross section of the suction chamber 30.

Volute wall 38 is integral with end wall 22 by means of rib 40 and integral with bottom wall 18 by means of rib 42. Volute wall 36 is integral with end wall 24 by means of rib 44. The first volute discharge port 46 from the pumping chamber 32 is generally diametrically opposite the second volute discharge port 48. Port 48 is below the axis of the suction port 28. A water recirculation port 50 is provided in the volute wall 38 immediately adjacent rib 42 as to be near the bottom of the pumping chamber 32. Port 50 is spaced from port 48 by approximately 45 arcuate degrees.

The casing 12 is provided on top wall with a boss 52 which is internally threaded. A discharge conduit 54 is threadedly coupled to boss 52. The top Wall 20 may also be provided with a priming port 56 which is closed by a removable plug. One or more drain ports 58 and 60, closed by a removable plug, are providedadjacent the bottom of casing 12 on side wall 14 to facilitate draining chamber 13. The pump 10 may be provided with legs 62 and 64 depending from the bottom wall 18.

An impeller 66 is provided within the pumping chamber 32. The suction eye of impeller 66 is aligned with the suction port 28. Impeller 66 is driven by motor 68. Motor 68 is provided with a flange 70 removably coupled to the side wall 16 by bolts or the like. Side wall 14 is provided with a machined area 72 to which a conduit may be bolted and through which the liquid to be pumped may be introduced into the suction chamber 30.

In operation, the second volute discharge port 48 is inoperative during priming. Water from chamber 13 is recirculated through port 50 into the pumping chamber 32. Water entering chamber 32 from port 50 and any air therein discharge through port 46 and separate in chamber 13. Hence, there is essentially no water left for discharge through port 48. The water near the bottom of chamber 13 is generally free of air and thereby facilitates faster priming by way of port 50. A seal is effected due to the fact that port 48 is below the axis of the impeller 66 and below the axis of the suction port 28. Thus, priming can be elfected so long as the amount of water in chamber 13 is up to the lowest edge of port 28. Since port 50 is less than 120 degrees and preferably only 45 degrees from port 48, the amount of water discharged from port 50 during the pumping cycle is minimal.

The present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof and, accordingly, reference should be made to the appended claims, rather than to the foregoing specification as indicating the scope of the invention.

It is claimed:

1. A self-priming centrifugal pump comprising a casing having walls defining a pumping chamber separated from an air separating outlet chamber, a rotatable impeller supported in said pumping chamber, said Walls including only first and second volutes, said volutes having overlapping ends and providing direct communication between said chambers, said volutes having discharge ports generally diametrically opposite one another, the discharge port of said second volute being below the axis of rotation of the impeller, the discharge port of said first volute being the only port above the axis of said impeller, the discharge port of said first volute being approximate ly arcuate degrees from a vertical line passing through the axis of rotation of said impeller, and said pumping chamber wall having a recirculation port near the bottom of the pumping chamber, said recirculation port providing direct communication between said chambers, with said recirculation port being not more than about arcuate degrees from said second volute discharge port.

2. A pump in accordance with claim 1 wherein said casing walls include a separating wall generally perpendicular to the axis of the impeller, said separating wall having a suction port aligned with the suction eye of the impeller, said separating wall being connected to one of the side walls of said casing by walls defining said volutes, and the walls defining said volutes being connected to end walls of said casing by ribs.

3. A pump in accordance with claim 1 including a rib extending from a casing wall to said second volute adjacent said recirculation port, the height of the rib corresponding to the height of said second volute.

References Cited UNITED STATES PATENTS 2,291,760 8/1942 Rupp 103-113 2,951,449 9/1960 Blarcom et al 1031 13 3,270,678 9/1966 Monica 103-113 2,945,448 7/1960 Frederick 103113 3,272,137 9/1966 Maitlen et al. 103113 3,276,385 10/1966 Marlow 1031 13 HENRY F. RADUAZO, Primary Examiner. 

